[0001] This invention relates generally to blends of fibers and yarns made therefrom. More
particularly, this invention relates to blends of carpet fibers having an excellent
overall combination of high bulk, high luster, firm hand and dye uniformity.
[0002] As used in this specification, the following terms have the associated meanings:
[0003] The term "modification ratio" or "MR" means the ratio of the radius R₂ of the circumscribed
circle to the radius R₁ of the inscribed circle as shown in FIG. 3.
[0004] The term "arm angle" or "A" is the angle formed by extension of the sides of an arm
as shown in FIG. 3.
[0005] The term "trilobal" refers to fibers having three lobes and a modification ratio
greater than 1. These trilobal fibers have lobes substantially without convex curves
where such convex curves are connected cusps along the contour of the lobe.
[0006] The term "pointed lobe trilobal" refers to a trilobal fiber cross-section where each
lobe is defined with reference to a single arm angle and each arm angle is greater
than 56 x MR
-1.5.
[0007] The term "standard trilobal" refers to a trilobal fiber cross-section where each
lobe is defined with reference to a single arm angle and each arm angle is less than
or equal to 56 x MR
-1.5.
[0008] The term "triangular lobal" refers to a fiber cross-section having lobes and a base
portion. The base portion without the lobes is approximately triangular. The lobes
are present at the apexes (tips) of the triangle. Exemplary triangular lobal fibers
are the smaller fibers shown in FIG. 3. Fibers of this cross-section are sometimes
referred to as having a "fox cross-section" because the cross-section resembles a
fox's head. The triangular lobal cross-section is characterized by three lobes and
two arm angles, A₀ and A₁. A₀ typically may range from 0° to 25° and A₁ typically
may range from 60° to 110°.
[0009] The term "fiber" refers to both filaments (strands of indefinite or continuous length)
and staple (strands of short and definite length).
[0010] In the production of fiber for use in carpets, it is desirable to produce fiber that
will provide carpet having a pleasing appearance with respect to cover, firmness and
luster. It is known to increase carpet cover per carpet weight by using trilobal fibers
having a high modification ratio. However, increasing the modification ratio usually
results in a reduction in luster. The present invention involves mixed filament yarns
which provide a surprisingly excellent balance of qualities when used in carpet.
[0011] U.S. Patent No. Re 29,352 to Newton discloses the broad concept of mixing fibers
and is primarily directed to an interlacing method for forming heather fabrics.
[0012] U.S. Patent No. 3,220,173 to Pitzl describes trilobal filaments having a modification
ratio falling within a range around a mean modification ratio in the range of 1.4
to 2.5. These filaments are not true mixed filaments, but rather a preset range of
cross-sections around a mean filament shape.
[0013] U.S. Patent No. 3,994,122 to Shah describes a blend of crimped staple fibers for
use in carpet. The blend comprises two components or groups of trilobal fibers of
the same denier, one group having a modification ratio between 1.6 and 1.9, and the
other group having a modification ratio between 2.2 and 2.5. While the blend of fibers
is described as providing improved appearance when compared to carpets produced from
fibers of either component alone, there is still substantial room for further improvements
along these lines.
[0014] U.S. Patent No. 4,001,369, also to Shah, describes a process for co-spinning the
trilobal filamentary yarn described in U.S. Patent No. 3,994,122.
[0015] U.S. Patent No. 4,472,481 to Snooks, Jr. et al. describes a trilobal fiber blend
having 70% to 90% by weight of a crimped trilobal polyamide fiber with a modification
ratio between 3 and 3.4 and a denier from 16 to 24, and 30% to 10% by weight of crimped
trilobal polyamide fibers with a modification ratio ranging from 1.7 to 2.4 and a
denier ranging from 6 to 12.
[0016] U.S. Patent Nos. 5,208,106 and 5,108,838, both to Tung, describe lobal fiber cross-sections
where the lobes have substantially convex curves connected by cusps along the contour
of each lobe.
[0017] U.S. Patent No. 4,770,938 to Peterson describes a trilobal fiber having an axially
extending hole in each lobe. The total cross-sectional void area is 5 to 12% and arm
angles of about 15° to 45°.
[0018] U.S. Patent No. 4,492,731 to Bankar et al. describes trilobal carpet fibers in a
specified range of modification ratio and related arm angles.
[0019] U.S. Patent No. 5,208,107 to Yeh et al. describes a trilobal fiber with a single
axially extending central void. The cross-sectional void area is 3-10%. The modification
ratio is between 3 and 10 and the arm angle is between about 7° and about 35°.
[0020] While blends of fibers have been shown to provide various results, there is still
room for improvement in the quality of appearance and texture of carpet yarns.
SUMMARY OF THE INVENTION
[0021] The present invention fills a void in the art by providing a blend of fibers comprising
about 51 to 90% by weight of base fibers (component (a)) selected from the group consisting
of triangular trilobal fibers having a modification ratio ranging from 2.4 to 3.4,
hollow pentagonal fibers, standard trilobal fibers having a modification ratio of
at least 2.6, pointed lobe trilobal fibers having a modification ratio of at least
2.6 and mixtures thereof; and about 10 to 49% by weight of accent fibers (component
(b)) selected from the group consisting of standard trilobal fibers having a modification
ratio ranging from 1.7 to 2.4 and pointed lobe trilobal fibers having a modification
ratio ranging from 2.0 to 2.9 and mixtures thereof. All the fibers have a denier per
filament within the range represented by the area enclosed by sides A, B, C, D and
E of FIG. 1. When both fibers (a) and fibers (b) are pointed lobe trilobal fibers
with the same modification ratio and denier, then fibers (a) are delustered and fibers
(b) are undelustered.
[0022] In an especially preferred embodiment, the present invention provides a blend of
fibers comprising 51 to 90% by weight of triangular trilobal fibers (component (a))
having a denier per filament of less than about 22 and 10 to 49% by weight of pointed
lobe trilobal fibers (component (b)) having a denier per filament of 18 to 36.
[0023] It is an object of the present invention to provide a carpet yarn for making carpet
with optimum luster, texture, hand, soil hiding and cover.
[0024] After reading the following description, related objects and advantages of the present
invention will be apparent to those ordinarily skilled in the art to which the invention
pertains.
[0025] FIG. 1 is a graph showing the area bounded by sides A, B, C, D and E which define
limits of the denier parameters for mixed fibers of the present invention.
[0026] FIG. 2 is a graph showing more preferred denier parameters for mixed fibers of the
present invention.
[0027] FIG. 3 is an enlarged cross-sectional representation of a mixed fiber yarn having
triangular trilobal base fibers and pointed lobe trilobal accent fibers, according
to the present invention.
[0028] FIG. 4 is an enlarged cross-sectional representation of another mixed fiber yarn
having hollow pentagonal base fibers and pointed lobe trilobal accent fibers, according
to the present invention.
[0029] FIG. 5 is an enlarged cross-sectional representation of yet another mixed fiber yarn
having standard trilobal base fibers and standard trilobal accent fibers, according
to the present invention.
[0030] FIG. 6A is an enlarged cross-sectional representation of two exemplary triangular
trilobal base fibers useful in the present invention.
[0031] FIG. 6B is an enlarged cross-sectional representation of an exemplary hollow pentagonal
base fiber useful in the present invention.
[0032] FIG. 6C is an enlarged cross-sectional representation of an exemplary standard trilobal
base fiber useful in the present invention.
[0033] FIG. 6D is an enlarged cross-sectional representation of two standard trilobal accent
fibers useful in the present invention.
[0034] FIG. 6E is an enlarged cross-sectional representation of two standard pointed lobe
trilobal fibers both useful as accent fibers and one useful as a base fiber (MR ≧
2.6) in the present invention.
[0035] To promote an understanding of the principles of the present invention, descriptions
of specific embodiments of the invention follow and specific language describes the
same. It will nevertheless be understood that no limitation of the scope of the invention
is thereby intended, and that such alterations and further modifications, and such
further applications of the principles of the invention as discussed are contemplated
as would normally occur to one ordinarily skilled in the art to which the invention
pertains.
[0036] The present invention is a blend of fibers which maintains high cover without sacrificing
luster when made into carpet. Surprisingly, in one preferred embodiment, this luster
is present and even enhanced when one of the component filaments is delustered.
[0037] The fiber blends of the present invention include 51 to 90% by weight of base fibers
(component (a)) and 10 to 49% by weight of accent fibers (component (b)). The fiber
components (a) and (b) have a denier per filament ("dpf") within the range represented
by the area enclosed by sides A, B, C, D and E of FIG. 1. More preferably, the range
of deniers is within the range represented by sides A', B', C', D' and E' of FIG.
2. If both component (a) and component (b) are pointed lobe trilobal fibers having
the same denier, modification ratio and arm angle, then component (a) is delustered
and component (b) is undelustered, i.e., bright.
[0038] The base fiber may be one or more of a group of common carpet fiber cross-sections.
Exemplary base fiber cross-sections are shown in FIGS. 6A, 6B, 6C and 6E. The cross-sections
in the figures are exemplary only and demonstrate the range limits of MR contemplated.
It will be readily understood by those of ordinary skill in the art that a continuum
of cross-sections having modification ratios between those shown in FIG. 6 are within
the scope of the invention. These carpet fiber cross-sections include triangular trilobal
fibers having a modification ratio ranging from 2.4 to 3.4 (FIG. 6A), hollow pentagonal
fibers (FIG. 6B), standard trilobal fibers having a modification ratio of at least
2.6 (FIG. 6C), pointed lobe trilobal fibers having a modification ratio of at least
2.6 (FIG. 6E MR=2.9) and mixtures of these fibers. Preferably, component (a) base
fibers are triangular trilobal fibers 21 as shown in FIG 3. They may or may not be
crimped according to known crimping methods such as air jet, stuffer box and false-twisting
methods. The base fibers may be symmetric or asymmetric due to unequal leg lengths,
leg angles or curvature in the legs. Component (a) base fibers preferably have a denier
ranging from 12 to 24. One or more axial voids may or may not be present. Axial voids
are those which are co-extensive with the longitudinal axis of the fiber. When voids
are present, a single central axial void is preferable. When hollow pentagonal fibers
are present, one or more voids may be present. A preferable pentagonal cross-section
31 is shown in FIG. 4.
[0039] Component (b) fibers are accent fibers which assist in providing the superior luster
of carpets made from the mixed fibers of the present invention. They also assist to
balance the cover, hand and soil hiding properties of carpets as well as improve carpet
dye uniformity. Component (b) accent fibers may or may not be crimped according to
standard crimping procedures for carpet fibers as described above. Exemplary accent
fiber cross-sections are shown in FIGS. 6D and 6E. The cross-sections in the figures
are exemplary only and demonstrate in some cases the range limits of MR contemplated.
It will be readily understood by those of ordinary skill in the art that a continuum
of cross-sections having modification ratios between those shown in FIG. 6 are within
the scope of the invention. Most preferably, the fibers of component (b) accent fibers
are pointed lobe trilobal fibers with a modification ratio ranging from 2.0 to 2.9
(FIG. 6E) or low modification ratio standard trilobal fibers with a modification ratio
ranging from 1.7 to 2.4 (FIG. 6D). Pointed trilobal fibers are also shown as the large
fibers 11 in FIG. 3. Component (b) accent fibers may or may not have at least one
central axial void. The cross-section may be symmetric or asymmetric due to unequal
leg lengths, leg angles or curvature in the legs.
[0040] It is contemplated that small amounts of other fibers may be present in the blends
such as, for example, conductive fibers of the type disclosed in U.S. Patent No. 4,255,487
to Sanders.
[0041] In a preferred embodiment, the base fiber (a) is delustered by the addition of up
to about 0.30% TiO₂. Surprisingly, it was discovered that the addition of the delustering
agent actually enhances the sparkle evident when the fiber is used as a carpet yarn
and constructed into carpet. Even more surprisingly, the enhanced sparkle effect was
observed where both base fiber (a) and accent fiber (b) are pointed lobe trilobals
which differ only in the presence or absence of a delustering agent.
[0042] An especially preferred embodiment of the present invention is represented in FIG.
3. Component (b) consists of pointed lobe trilobal fibers 11 which are present at
10% to 49%, preferably 10% to 20%, by weight. These fibers preferably have a modification
ratio ranging from 2.3 to 2.8 and a denier per filament ranging from 18 to 36 but
preferably at least 22. Although voids 12 are shown, they may or may not be present.
Most preferably, pointed lobe trilobal fibers 11 are bright.
[0043] The remaining 51% to 90% and preferably 80% to 90% of fibers in FIG. 3 are primarily
component (a) and consist of fibers 21 having a generally triangular trilobal cross-section
with a modification ratio ranging from 2.7 to 3.0 and a denier per filament ranging
from 16 to 22 but preferably less than 20. Component (a) may or may not have voids.
Preferably, triangular trilobal fibers 21 are delustered with 0.10% to 0.15% by weight
TiO₂.
[0044] Another embodiment of the invention is shown in FIG. 4. Component (b) consists of
10% to 49% of pointed lobe trilobal fibers 11 having a denier per filament of from
about 18 to about 36. Component (a) consists of 51% to 90% of hollow pentagonal fibers
31.
[0045] A further embodiment of the invention is shown in FIG. 5. Component (b) consists
of 10% to 49% of standard trilobal fibers 51 having a modification ratio of 2.4 and
a denier per filament of from about 18 to 36. Component (a) consists of 51% to 90%
of standard trilobal fibers 53 having a modification ratio greater than 2.6 and an
arm angle less than 13.4.
[0046] Polyamides useful in preparing the fiber blends of the invention include nylon 6,6
(polyhexamethylene adipimide) and nylon 6 (poly-ε-caprolactam). Other polyamides include
the common nylons, such as nylon 11, nylon 6,10 and copolymers of nylon 6,6 and nylon
6, such as nylon 6,6/6 and nylon 6,6/6TA, where 6TA is hexamethylene terephthalamide
units. Polyesters and other fiber forming polymers are useful as well.
[0047] The fibers of the blends may contain conventional additives incorporated therein,
such as delusterants (e.g., TiO₂), heat and light stabilizers, dye agents, and the
like. Normally, such additives are added to the monomers during polymerization or
to molten polymer prior to fiber formation. The fibers may be pigmented or conventionally
dyed.
[0048] Fiber blends of the present invention may be melt spun according to the known or
later developed methods for spinning the type of polymer. Conventional winding or
spin-draw-texture processes may be used.
[0049] A fiber blend in the form of continuous filament yarn may be conveniently prepared
by forming the blend during melt spinning. This can be accomplished by using a single
spinneret adapted to spin component (a) and component (b) in the appropriate ratio
which are then converged to form yarn. When a single spinneret is used the different
deniers per filament and the different cross-sections should be controlled through
spinneret design and precise manufacturing. Alternatively, separate spinnerets may
be used for forming each of the component filaments. The filaments are then combined
in the appropriate ratio to form yarn. The yarn may be drawtextured to provide a crimped
yarn, or a plurality of such yarns may be combined to form a tow.
[0050] Staple yarn may be used but continuous filaments are preferred.
[0051] Another aspect of this invention is a carpet made with the mixed filament yarn of
the present invention. The yarn may be tufted or woven according to known procedures
for doing so. Especially, the yarn makes a superior level loop carpet having very
evident sparkle.
[0052] Further preferred embodiments of the instant invention can be summerized as set forth
below.
[0053] Blends as defined and described in claim 1, wherein one or more of the following
features are satisfied:
A) Base fibers a) are triangular trilobal fibers,
B) fibers a) and b) are made of nylon-6,
C) fibers a) and b) are crimped,
D) blends comprising from 40 to 260 total filaments,
E) blends wherein said filaments are in the form of a single yarn,
F) blends wherein fibers a) and b) are undelustered
G) blends wherein base fibers a) are triangular trilobal, fibers having a modification
ratio ranging from 25 to 32 and a central axial void,
H) blends wherein fibers b) are pointed lobe trilobal fibers with a modification ratio
ranging from 2.0 to 2.9 and
preferably also having a central axial void.
[0054] More preferred embodiments base on the blends as claimed in claim 2 are as follows:
I) Blends wherein fibers a) and b) are continuous filaments, preferably wherein the
total number of filaments as in the range of from 68 to 136,
K) blends comprising triangular trilobal nylon-6 fibers containing up to 0.30 wt%
titanium dioxide (TiO₂),
L) blends wherein the fibers b) (pointedlobe trilobal fibers) have a modification
ratio of from 2.3 to 2.8,
M) blends wherein said triangular trilobal fibers have a modification ratio of 2.5
to 3.0.
[0055] The invention will be described by reference to the following detailed Examples.
The Examples are set forth by way of illustration, and are not intended to limit the
scope of the invention. In the Examples, all parts are part by weight unless otherwise
specified.
Methods:
[0056] In the Examples below, carpet luster, hand, tip definition and cover were assessed
by a panel of at least four persons.
EXAMPLE 1
[0057] A mixed cross-section bulked continuous filament ("BCF") yarn is made with two cross-sectional
components. Both components are bright (undelustered) filaments made from nylon 6
polymer having 2.7 relative viscosity (RV) as measured in a 1 g/100 ml solution in
96% by weight sulfuric acid at 25°C. The two components are made separately using
a spin-winding process.
[0058] For component (a), nylon 6 at 270°C is supplied to a spinneret to achieve a throughput
of 176 g/min. The quench air flow is 82 ft/min (25 m/min). For component (b), nylon
6 at 275°C is supplied to a spinneret to achieve a throughput of 71.5 g/min. The quench
air flow is 80 ft/min (24.4 m/min). The winding speed for both components is 650 m/min.
[0059] Component (a) is spun using a 68-hole triangular trilobal spinneret and component
(b) is spun using a spinneret with 14 Y-shaped orifices. Spin-winding conditions for
these two component feed yarns are adjusted so the yarns have similar tensile properties.
The two different yarns are fed together into a drawtexturing machine.
[0060] A 3.0 mechanical draw ratio is applied and the other operating conditions are adjusted
to obtain a target yarn with 12.5% hot water bulk and 40 tangles per meter. The resultant
BCF yarn comprises: (a) 68 triangular trilobal filaments with a 2.9 modification ratio
and 15.0 dpf and (b) 14 standard trilobal filaments with a 1.8 modification ratio
and 28.6 dpf. The mixed yarn is, therefore, 1420 denier with 82 filaments.
[0061] The mixed cross-section BCF yarn is then cable twisted at 4.0 twists per inch, Superba
heatset and tufted into 35 oz/sqyd (1183 g/m²), 5/8" (15.9 mm) pile height, and 5/32"
(3.97 mm) gauge cut pile carpet. The sample carpet of filament mixture exhibits significantly
brighter luster with very little loss in cover power as compared to a carpet made
of 100% triangular trilobal filaments with similar carpet construction.
EXAMPLE 2
[0062] A mixed cross-section BCF yarn is made with two components. Both components are made
from a 2.7 RV(measured in a 1 g/100 ml solution in 96% by weight sulfuric acid at
25°C nylon 6 polymer, and have the same hollow pointed lobe trilobal cross-section
of 2.7 modification ratio. The differences between these two components are: 1) one
is bright and the other is delustered; and (2) they have different filament deniers.
The two components are made separately in a spin-winding process.
[0063] For component (a), nylon 6 at 270°C is supplied to a spinneret to achieve a throughput
of 176 g/min. The quench air flow is 82 ft/min (25 m/min). For component (b), nylon
6 at 275°C is supplied to a spinneret to achieve a throughput of 71.5 g/min. The quench
air flow is 80 ft/min (24.4 m/min). The winding speed for both components is 650 m/min.
[0064] Component (a) is spun using a spinneret with 68 hollow pointed lobe trilobal orifices.
A master batch nylon 6 chip containing 30% TiO₂ is fed to the extruder. The master
batch feed rate is controlled to obtain a spun yarn containing 0.3% TiO₂. Component
(b) is spun using a 14-hole spinneret with the orifice shape identical to those for
component (a). Spin-winding conditions for these two component feed yarns are adjusted
to make the two components have similar tensile properties.
[0065] The two different yarns are then fed together into a drawtexturing machine. A 3.0
mechanical draw ratio is applied and the draw godet temperature and interlacing air
pressure are adjusted to obtain a BCF yarn with 12.5% hot water bulk and 40 tangles
per meter. The resultant BCF yarn comprises: (a) 68 delustered filaments with 20.3
dpf and (b) 14 bright filaments with 30 dpf. The whole yarn is, therefore, 1800 denier
with 82 filaments.
[0066] The mixed cross-section BCF yarn is then air entangled, space dyed and tufted into
level loop carpets with 1/8" (3.17 mm) gauge, 3/16 (4.76 mm) pile height, and 8, 9,
and 10 stiches per inch (3.15, 3.54 and 3.94 stitches per cm). These sample carpets
of filament mixture exhibit high cover power, firm hand and high sparkling effect
EXAMPLE 3
[0067] A BCF yarn with mixed cross-section filaments is made using a spin-drawtexture process.
All filaments are made from undelustered nylon 6 polymer of 2.7 RV as measured in
a 1 g/100 ml solution in 96% by weight sulfuric acid at 25°C. A single spinneret having
two different kinds of capillaries is used to make the yarn so that the yarn contains
two filament components. For both components, nylon 6 at 265°C is supplied at 252
g/min to the spinneret. The quench air flow is 90 ft/min (27.4 m/min). The spinning
speed is 800 m/min and the drawing speed is 2400 m/min. The spin and draw godets are
set at 50°C and 150°C, respectively.
[0068] Component (a) consists of 56 filaments having a triangular trilobal cross-section,
2.80 average modification ratio and about 13.7 dpf. Component (b) contains 13 filaments
having an asymmetric pointed lobe trilobal cross-section, 2.87 average modification
ratio and about 26.8 dpf. The mixed yarn is, therefore, 1100 denier with 69 filaments.
[0069] The mixed cross-section BCF yarn is then cable twisted at 4.5 twists per inch, autoclave
heatset and tufted into a 9/16" (14.28 mm) pile height, 1/8" (3.17 mm) gauge, 8 stitches
per inch (3.15 stitches per cm), cut pile carpet and a 3/16" (4.76 mm) pile height,
1/10" (2.54 mm) gauge, 8 stitches per inch (3.15 stitches per cm) level loop carpet.
Compared to carpets of the same constructions made of 100% triangular trilobal cross-section
filaments produced under identical spin-drawtexturing conditions, the mixed cross-section
carpets exhibit significantly brighter luster and similar cover power.